Carrying apparatus and image forming apparatus

ABSTRACT

The carrying apparatus comprises a carrying device for carrying an object to be carried, along a carrying route, a control device for temporarily stopping and holding the object carried by the carrying device, on the carrying route, if necessary, an open/close door provided in the carrying device, for opening/closing the carrying route, and a limiter device for limiting opening of the open/close door, based on detection of the object by the detection device.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a carrying apparatus forconveying a paper sheet and an image forming apparatus which arecomprised, for example, in an electrophotographic copying machine.

[0002] In many electrophotographic copying machines, images can beformed on both surfaces of a paper sheet. To form images on bothsurfaces in this kind of copying machine, a paper sheet is supplied froma paper sheet feed cassette to an image forming section through a papersheet carrying route (hereinafter simply called ADU), and an image isformed on one surface. The paper sheet on which an image has been formedis then stacked and contained in an intermediate tray. Subsequently, thepaper sheet stacked and contained in the intermediate tray is fed againto the image forming section, and an image is then formed on its backsurface. Thus, images are formed on both surfaces of a paper sheet whichis then fed out onto a sheet discharge tray.

[0003] Meanwhile, electrostatic charges have been applied to papersheets stacked on the intermediate tray, for example, through a transferprocess at the image forming section. Therefore, paper sheets easilytend to be fed stuck together due to static electricity, when they arefed again from the intermediate tray.

[0004] In addition, since a paper sheet having a surface on which animage has been formed must once be stacked and contained in theintermediate tray, an image cannot be formed sequentially on its backsurface. Time loss is therefore caused so that the image formingefficiency is lowered.

[0005] To solve the above-described problems that layered paper sheetsare fed and the image forming efficiency is lowered, a development hasbeen made in an electrophotographic copying machine which adoptsso-called non-stack ADU.

[0006] That is, this kind of electrophotographic copying machine carriesout continuous image formation on surfaces of a plurality of sheets,excluding the intermediate tray from the ADU. Thereafter, these papersheets are directly sent to the image forming section, reversed by areverse carrying means, and an image is formed on the back surface ofthe paper sheet.

[0007] In some cases, the non-stack ADU is used with an accountingdevice such as a coin controller attached thereto. If data of total 4pages are double-side-printed on two paper sheets in anelectrophotographic copying machine attached with the accounting device,for example, there may be a case that inserted money runs short at thetime point when printing on pages 1, 2, and 4 pages.

[0008] In this case, the paper sheet on which the third page should beprinted should be discharged without carrying out printing or should bekept in the ADU in the apparatus.

[0009] Meanwhile, the non-stack ADU is opened/closed in accordance withan operation of opening/closing an open/close door. If a paper sheetjams en route, the open/close door is opened to remove the paper sheet.

[0010] However, in a conventional apparatus, the open/close door is keptpermanently openable, and there is a case that the door is opened with apaper sheet still in the ADU. In this case, there is a drawback that thepaper sheet in the ADU falls drops to the ground and gets dirty.

BRIEF SUMMARY OF THE INVENTION

[0011] The present invention has been made in view of the actualsituation as described above, and has an object of providing a carryingapparatus and an image forming apparatus in which the carrying route (areverse carrying route) is inhibited from opening when an object to becarried (an object to which an image should be transferred) is kept on acarrying route (a reverse carrying route).

[0012] A carrying apparatus according to the present inventioncomprises: a carrying device for carrying an object to be carried, alonga carrying route; a control device for temporarily stopping and holdingthe object carried by the carrying device, on the carrying route, ifnecessary; an open/close door provided in the carrying device, foropening/closing the carrying route; and a limiter device for limitingopening of the open/close door, based on detection of the object by thedetection device.

[0013] An image forming apparatus according to the present inventioncomprises: an image forming device for forming an image on an imagecarrier; a transfer device for transferring the image formed by theimage forming device, to an object to which the image should betransferred; a reverse carrying device for carrying the object having asurface to which the image has been transferred, along a reversecarrying route, thereby to reverse and feed the object again to thetransfer device, and to transfer an image on another surface of theobject; a control device for temporarily stopping and holding the objectcarried by the reverse carrying device, on the carrying route, ifnecessary; an open/close door provided in the carrying device, foropening/closing the carrying route; a detection device for detecting theobject held on the reverse carrying route; and a limiter device forlimiting opening of the open/close door, based on detection of theobject by the detection device.

[0014] Additional objects and advantages of the invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0015] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate presently preferredembodiments of the invention, and together with the general descriptiongiven above and the detailed description of the embodiments given below,serve to explain the principles of the invention.

[0016]FIG. 1 is a schematic structural view showing anelectrophotographic copying machine according to an embodiment of thepresent invention;

[0017]FIG. 2 is a view showing a state in which a paper sheet is beingfed to an image transfer section;

[0018]FIG. 3 is a view showing a state in which a paper sheet is beingfed out from the image transfer section with an image transferredthereto;

[0019]FIG. 4 is a view showing a state in which the paper sheet fed outfrom the image transfer section is being fed in the reverse direction,and a following paper sheet is being fed into the image transfersection;

[0020]FIG. 5 is a view showing a state in which the paper sheet fed inthe reverse direction is being fed into a reverse carrying route, and afollowing paper sheet is being fed out from the image transfer sectionwith an image transferred thereto;

[0021]FIG. 6 is a view showing a state in which the paper sheet fed intothe reverse carrying route is being carried, and the following papersheet is being fed in the reverse direction;

[0022]FIG. 7 is a view showing a state in which an image is beingtransferred to the back surface of the paper sheet fed out from thereverse carrying route, and the following paper sheet is being fed intothe reverse carrying route and carried;

[0023]FIG. 8 is a view showing a state in which the paper sheet with animage formed on its back surface is being discharged onto a sheetdischarge tray, and an image is being transferred to the back surface ofthe following paper sheet and carried;

[0024]FIG. 9 is a view showing a state in which the following papersheet with an image formed on its back surface is discharged onto thesheet discharge tray;

[0025]FIG. 10 is an enlarged view showing a lock device for locking anopen/close door;

[0026]FIG. 11 is a view showing a state in which a lock of theopen/close door is released;

[0027]FIG. 12 is a block diagram showing the drive control system of thelock device;

[0028]FIG. 13 is a view showing a state in which the open/close door isopened; and

[0029]FIG. 14 is a block diagram showing the control system of a warningdisplay device as a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In the following, the present invention will be explained withreference to an embodiment shown in the drawings.

[0031]FIG. 1 is a structural view showing an electrophotographic machineas an image forming apparatus according to an embodiment of the presentinvention.

[0032] The electrophotographic machine 1 comprises an apparatus body 1.An image forming section 2 for forming an image on a paper sheet as anobject to be carried (e.g., a transfer-target material) in anelectrostatic photographic method, a sheet feeder 3 for carrying andsupplying a paper sheet for the image forming section 2, and a reversecarrying apparatus 4 for reversing the front and back surfaces of thepaper sheet and for returning the paper sheet to the sheet feeder 3.Since the reverse carrying apparatus 4 does not comprise an intermediatetray, the apparatus serves as a so-called non-stack ADU.

[0033] The image forming section 2 comprises rotatably a photosensitivedrum 6 as an image carrier. Provided in the peripheral part of thephotosensitive drum 6 are members for executing a so-calledelectrostatic photographic process by means of a process CPU (notshown).

[0034] More specifically, the photosensitive drum 6 is constructed by anapplication type OPC charged in the minus polarity, and thisphotosensitive drum 6 includes a conductive base member and aphotosensitive layer covering the surface of the conductive base member.The photosensitive layer has a film thickness of 15 to 30 λm and adielectric constant of 2.0 to 5.0. The conductive base member of thephotosensitive drum 6 is grounded.

[0035] Provided in the peripheral part of the photosensitive drum 6along the rotating direction thereof are a charger 7, an opticalscanning system (not shown) for emitting imaging light 8, a developingdevice 9, a transfer device 10, a separator 11, a cleaning device 12,and a discharger 13.

[0036] The sheet feeder 3 includes a sheet feed cassette 15 and a maincarrying route 16 for carrying a paper sheet supplied from the sheetfeed cassette 15 to the upside. Paper sheets P are contained in thesheet feed cassette 15, and are fed one after another by rotation of thesheet feed roller 14.

[0037] The main carrying route 16 is provided along the verticaldirection. Paired carrying rollers 17, paired resist rollers 18, animage transfer section 19, paired fixing rollers 20, and paireddischarge rollers 21 are provided respectively from the side of thelower part to the side of the upper part on the main carrying route 16.A sheet discharge tray 22 is provided in the side of the paireddischarge rollers 21 in which paper sheets are discharged.

[0038] The reverse carrying device 4 has a reverse carrying route 24which connects the sheet discharge side of the paired rollers 20 withthe sheet introducing side of the paired resist rollers 18. The reversecarrying route 24 is constructed by a horizontal part 24 a, a cornerpart 24 b in the upper side, a vertical part 24 c, a corner part 24 d inthe lower side, and a substantial horizontal part 24 e. The corner part24 b in the upper side, the vertical part 24 c, and the corner part 24 din the lower side are respectively provided with pairs of carryingrollers 25 a, 25 b, and 25 c.

[0039] Upper and lower detection sensors 27 a and 27 b as detectiondevices for detecting paper sheets P are provided respectively betweenthe paired carrying rollers 25 a and 25 c and between the pairedcarrying rollers 25 b and 25 c.

[0040] In addition, the reverse carrying device 4 has an open/close door30 for opening/closing the reverse carrying route 24. The open/closedoor 30 is rotatably supported, in its lower side, on the apparatus body1 by a support shaft. A lock device 32 as a limiter device is providedin the upper side of the open/close door 30.

[0041]FIG. 10 is an enlarged view of the lock device 32. The lock device32 is constructed by a solenoid 33, an operation lever 34 which moves upand down in accordance with on and off of the solenoid 33, and a locklever 35 having a rear end part connected with an upper end part of theoperation lever 34. The lock lever 35 has an intermediate part rotatablysupported on a support shaft 36 and has a top end part where a hook part35 a is formed. The hook part 35 a of the lock lever 35 is detachablyengaged with an engage gap part 1 a formed on the apparatus body 1. Aspring member 38 is connected between the support shaft 36 and the hookpart 35 a, and the lock lever 35 is pressed upward by the spring member38.

[0042]FIG. 10 shows a state where the solenoid 33 is turned on. When thesolenoid 33 is turned on, the lock lever 33 is rotated downward aboutthe support shaft 36, against the pressing force of the spring member38, so that its hook part is engaged with the engaging gap part 1 athereby to lock the open/close door 30.

[0043] When the solenoid 33 is turned off, the lock lever 35 is pushedupward by the spring member 38, so that its hook part 35 a is releasedfrom the engaging gap part 1 a to release the lock of the open/closedoor 30.

[0044]FIG. 12 is a block diagram showing the drive control system of thereverse carrying apparatus 4.

[0045] The upper and lower detection sensors 27 a and 27 b are connectedto a control device 40 through a signal circuit, and the control device40 is connected to the solenoid 33 through a control circuit. Thesolenoid 33 is connected with the lock lever 35.

[0046] Also, the control device 40 is connected with a fee counter 39through a signal circuit. The fee counter 39 is attached to anaccounting device such as a coin controller or the like which will beexplained later. The fee counter 39 counts inserted money and calculatesthe balance of use fee.

[0047] The control device 40 receives a money insertion signal or ano-balance signal concerning the fee, thereby to control rotation of thepaired carrying rollers 24 a to 24 c on the reverse carry route 24.

[0048] Also, the control device 40 excites the solenoid 33 to lock theopen/close door 30 when a paper sheet P is temporarily kept on thereverse carrying route 24, as will be described later.

[0049] Next, explanation will be made of double-side image formingoperation with reference to FIGS. 1 to 9.

[0050] When forming images on both sides, the surface of thephotosensitive drum 6 is charged by the charger 7 at first, and imaginglight 8 is irradiated on the surface of the charged photosensitive drum6, so that an electrostatic latent image corresponding to an originaldocument image is formed on the surface of the charged photosensitivedrum 6. This electrostatic latent image is sent to the developing device9 by rotation of the photosensitive drum 6 and is supplied with magnetictoner as a developing agent from the developing device 9, to form amagnetic toner image.

[0051] At this time, a paper sheet P is supplied by rotation of thesheet feed roller 14 and is clamped and carried by the paired carryingrollers 17. This paper sheet P is aligned by the paired resist rollers18 and is thereafter supplied to the image transfer section 19 betweenthe photosensitive drum 6 and the transfer device 10. Here, the magnetictoner image on the photosensitive drum 6 is transferred to the papersheet P. The paper sheet P on which the magnetic toner image has beentransferred is separated from the photosensitive drum 6 and carried bythe operation of the separator 11. As shown in FIG. 3, this paper sheetis then supplied to the paired fixing rollers 20 where the transferredtoner image is fixed to the paper sheet P and is fed out toward thedischarge tray 22.

[0052] After the paper sheet P is fed by a predetermined amount, thepaper sheet P is fed in the reverse direction, as shown in FIG. 4, and afollowing paper sheet P is carried along the feed carrying route 16.Subsequently, as shown in FIG. 5, the preceding paper sheet P is carriedout along the reverse carrying route 24, and a toner image on thephotosensitive drum 6 is transferred to the following paper sheet Pwhich is then fed out. After the following paper sheet P is fed by apredetermined amount, it is also fed in the reverse direction as shownin FIG. 6 while the preceding paper sheet P is also carried continuouslyalong the reverse carrying route 24. Thereafter, the preceding papersheet P is fed into the image transfer section 19, reversed as shown inFIG. 7, and a toner image is transferred to the back surface thereof.The following paper sheet P is carried along the reverse carrying route24.

[0053] The preceding paper sheet P with a toner image transferred to itsback surface is discharged on the discharge tray 22, as shown in FIG. 8.At this time, the following paper sheet P reversed is fed to the imagetransfer section 19, and a toner image is transferred to its backsurface. Thereafter, the following paper sheet P is fed as shown in FIG.9, and is carried out onto the discharge tray 22.

[0054] Meanwhile, there is a case of using the above-describedstack-less ADU attached with an accounting device such as a coincontroller. For example, if data of four pages should be printed on bothsurfaces of two paper sheets by an electrophotographic copying machine,there is a case that inserted money runs short at the time point whenprinting of the first, second, and fourth pages are finished. In thiscase, the paper sheet is directly discharged without printing the thirdpage to be printed or kept on the reverse carrying route 24.

[0055] However, it will be unkind to the user to discharge the papersheets P without printing the third page.

[0056] Otherwise, if the paper sheet P is kept on the reverse carryingroute 24, the open/close door 30 is opened as shown in FIG. 13 and thereverse carrying route 24 is also opened. Then, the paired carryingrollers 25 a, 25 b, and 25 c are parted, so the paper sheet P falls.

[0057] Hence, in the present invention, if the inserted money runs shortat the time point when printing is finished with respect to the first,second, and fourth pages and a paper sheet P is kept on the reversecarrying route 24, the open/close door 30 is locked and inhibited fromopening.

[0058] That is, if a paper sheet P is kept in the middle of the reversecarrying route 24, the paper sheet P is detected by the detection sensor27 a. A detection signal thereof is transmitted to the control device40. Upon transmission of the detection signal, the control device 40excites the solenoid 33. Upon this excitation, the operation lever 34 ismoved upward thereby pushing up the lock lever 35. In this manner, asshown in FIG. 10, the lock lever 35 is rotated downward against thepressing force of the spring member 38 about the support shaft 36, sothat its hook part 35 a is engaged with the engaging gap part 1 a. Theopen/close door 30 is locked by this engagement, and cannot be openedeven if an operator attempts to open it.

[0059] Accordingly, the paper sheet P kept on the route does not fallthrough the open/close door 30, and thus, paper sheets P are preventedfrom being soiled as in a conventional apparatus.

[0060] When the paper sheet P once kept in the middle of the reversecarrying route 24 is fed out and is not detected any more by thedetection sensor 27 a, the solenoid 33 is turned off by the controldevice 40. As a result, the lock lever 35 is pushed up by the springmember 38, as shown in FIG. 11, so that its hook part 35 a is releasedfrom the engaging gap part 1 a thereby release the lock.

[0061]FIG. 14 shows a second embodiment of the present invention.

[0062] Explanation of the same parts as those shown in FIG. 12 will bedenoted by the same references, and explanation thereof will be omittedherefrom.

[0063] In the first embodiment described above, the open/close door 30is locked by the lock device 32. In the second embodiment, however, awarning display device 41 is connected to the control device 40 througha control circuit.

[0064] In the second embodiment, a paper sheet P is detected by an upperor lower detection sensor 27 a or 27 b, and detection informationthereof is supplied to the control device 40. The control device 40 thencontrols the warning display device 41 to display an alarm indicationthat the open/close door 30 may not be opened. Thus, an operator can seethe warning and refrain from opening the open/close door 30.

[0065] Accordingly, in the second embodiment, it is possible to preventpaper sheets P kept on the reverse carrying route 24 from falling downthrough an opened open/close door 30 like the first embodiment.

[0066] Additional advantages and modifications will readily occur tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details and representativeembodiments shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

What is claimed is:
 1. A carrying apparatus comprising: a carryingdevice for carrying an object to be carried, along a carrying route; acontrol device for temporarily stopping and holding the object carriedby the carrying device, on the carrying route, if necessary; anopen/close door provided in the carrying device, for opening/closing thecarrying route; and a limiter device for limiting opening of theopen/close door, based on detection of the object by the detectiondevice.
 2. The carrying apparatus according to claim 1, wherein thecarrying device has paired carrying rollers for clamping and carryingthe object.
 3. The carrying apparatus according to claim 1, wherein thedetection device is a detection sensor for optically detecting theobject.
 4. The carrying apparatus according to claim 2, wherein thepaired carrying rollers are brought into contact with each other andseparated from each other in accordance with the opening/closingoperation of the open/close door.
 5. A carrying apparatus comprising: acarrying device for carrying an object to be carried, along a carryingroute; a control device for temporarily stopping and holding the objectcarried by the carrying device, on the carrying route, if necessary; anopen/close door provided in the carrying device, for opening/closing thecarrying route; and a warning display device for displaying an alarmindication for inhibiting opening of the carrying route.
 6. An imageforming apparatus comprising: an image forming device for forming animage on an image carrier; a transfer device for transferring the imageformed by the image forming device, to an object to which the imageshould be transferred; a reverse carrying device for carrying the objecthaving a surface to which the image has been transferred, along areverse carrying route, thereby to reverse and feed the object again tothe transfer device, and to transfer an image on another surface of theobject; a control device for temporarily stopping and holding the objectcarried by the reverse carrying device, on the carrying route, ifnecessary; an open/close door provided in the carrying device, foropening/closing the carrying route; a detection device for detecting theobject held on the reverse carrying route; and a limiter device forlimiting opening of the open/close door, based on detection of theobject by the detection device.
 7. The image forming apparatus accordingto claim 6, wherein the carrying device has paired carrying rollers forclamping and carrying the object.
 8. The image forming apparatusaccording to claim 6, wherein the detection device is a detection sensorfor optically detecting the object.
 9. The image forming apparatusaccording to claim 7, wherein the paired carrying rollers are broughtinto contact with each other and separated from each other in accordancewith opening/closing operation of the open/close door.
 10. An imageforming apparatus comprising: an image forming device for forming animage on an image carrier; a transfer device for transferring the imageformed by the image forming device, to an object to which the imageshould be transferred; a reverse carrying device for carrying the objecthaving a surface to which the image has been transferred, along areverse carrying route, thereby to reverse and feed the object again tothe transfer device, and to transfer an image on another surface of theobject; a control device for temporarily stopping and holding the objectcarried by the reverse carrying device, on the carrying route, ifnecessary; an open/close door provided in the carrying device, foropening/closing the carrying route; a detection device for detecting theobject held on the reverse carrying route; and a warning display devicefor displaying an alarm indication for inhibiting opening of thecarrying route, based on detection of the object by the detectiondevice.